Taking into account hysterectomies in the analysis of cancer mortality has led to these rates being underestimated.

The vaccine against cervical cancer has been offered in the UK since 2008Reuters

Cervical cancer mortality rates may be underestimated, particularly among black women. A possible reason for this is that analyses usually take into account women who have had their cervix surgically removed, even though they are not at risk of developing the disease.

Some 12,000 women in the US and 3,000 in the UK are diagnosed each year with cervical cancer. In both countries, the disease is thought to be more prevalent among racial minorities, wherein there are higher mortality rates.

"In the UK, the data does suggest that there are ethnic differences. We estimate that 8.2 to 8.7 out of 100,000 white women get diagnosed with cervical cancer, and 6.3 to 11.3 black women. We don't know the reason for this but it may be down to lifestyle and behavioural differences", Rachel Orritt, Cancer Research UK's health information officer, toldIBTimes UK.

Recent studies have nevertheless suggested that the gap between black and white women is closing, and that there had been a decline in mortality rates among black women.

The study, published in the journal Cancer, investigates whether that is really the case, arguing that analysis of mortality rates is often flawed because women who have gone through hysterectomies are included when they are no longer at risk of cancer due to their cervix having been removed.

"We sought to estimate the hysterectomy-corrected US annual age-specific and age-standardises cervical cancer mortality rates over the last decade to demonstrate the true magnitude of racial disparity", the authors write.

Mortality rate increase

The scientists from the Johns Hopkins Bloomberg School of Public Health (US) used a large, nationally representative sample to estimate the prevalence of hysterectomy. They also obtained estimates of cervical cancer mortality rates between 2002 and 2012 from two sources: the National Center for Health Statistics and the NCI Surveillance, Epidemiology, and End Results Mortality Database.

Analysing the data, they found out that the total mortality rates for cervical cancer had been underestimated. This underestimation has the most profound effect in black women
because they are the group with the highest prevalence of hysterectomy.

They estimated that the mortality rate for white women was 47% higher than previously thought, but for black women it was 77% higher. Taking hysterectomy into account, it stood for them at 10.1 per 100,000 women compared with 5.7 per 100,000 previously.

Another interesting finding was that many women dying were over the age of 65, which in the US represents a cut-off point wherein guidelines no longer recommend screening. Thus the study could contribute to changing these guidelines to better take into account the reality of cervical cancer mortality.

Screening for cervical cancer

Screening is a huge part of effective cervical cancer diagnosis and prevention. The cell lining the surface of the cervix undergo a series of changes throughout a woman's life. Sometimes, some of these cells might become cancerous. Screening for cervical cancer involves collecting a sample of these cells for analysis to check for any abnormal cells.

It is important to note that most abnormal results are caused by an infection or the presence of treatable precancerous cells, not by cancer.

"Less than a woman in 20 gets an abnormal result. This does not mean that they will be diagnosed with cancer, but it might be an indication that they may be at risk in the future. That is how screening can be used as a prevention tool, identifying the women who may go on to develop cervical cancer, and offering proper follow-up", Orritt says.

The majority of cervical cancer cases are caused by the human papilloma virus (HPV). Since 2008, a vaccine has been offered in the UK to girls aged 12 and 13.

For women who are diagnosed, treatment options vary depending on how early the cancer has been diagnosed. In an early stage, it's usually possible to treat it using surgery potentially combined with radiotherapy. For later stages, radiotherapy and chemotherapy are usually used.